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My T-REX 450 tail wags like crazy, have to let low gyro gain


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maruey
Hopping Maniac
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Joined: 19 Nov 2007
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PostPosted: Mon Nov 19, 2007 10:28 pm
PostPost subject: My T-REX 450 tail wags like crazy, have to let low gyro gain
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Hello everyone, another newbie here.

I've got my self a T-REX 450 S and finally mastered hovering! Very Happy Now I need help from all you avid pilots, my T-REX tail wags all the time! I have to set the gyro gain really low (around 15) to stop it, but it doesn't really stop either. And with the gyro gain set that low, the helicopter just doesn't hold the nose all that well (if at all).

I've balanced my main blade and made sure no part vibrate. But still the problem persists. Please help me with this one. I am so frustrated and I dream of it flying stable!
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vrthai
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PostPosted: Mon Nov 26, 2007 11:02 am
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Um, if you balanced everything then it should have been fine. Having to set gyro gain low is almost always caused by some form of vibration. Are you sure every component is locked down?
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maruey
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PostPosted: Wed Nov 28, 2007 12:25 pm
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vrthai wrote:
Are you sure every component is locked down?


Actually, the flybar can move back and forth. But there doesn't seem to be anything I can do about it. I've screwed it in as far as it will go but still it won't exactly lock down. It can slide about 1 - 2 mm.

Could this be causing the vibration?
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hound15
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PostPosted: Wed Nov 28, 2007 9:22 pm
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maruey wrote:
vrthai wrote:
Are you sure every component is locked down?


Actually, the flybar can move back and forth. But there doesn't seem to be anything I can do about it. I've screwed it in as far as it will go but still it won't exactly lock down. It can slide about 1 - 2 mm.

Could this be causing the vibration?


Yes that could definitely be causing the vibration. The fly bar shouldn't be moving around. If it's screwed in all the way and still moves, try fitting some of those tiny rings between the extra space.
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maruey
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PostPosted: Thu Nov 29, 2007 8:30 pm
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hound15 wrote:
Yes that could definitely be causing the vibration. The fly bar shouldn't be moving around. If it's screwed in all the way and still moves, try fitting some of those tiny rings between the extra space.


Thanks hound15, I tried that and it works! Very Happy But not completely. I mean the vibration decreased noticeably but the tail still wags a bit. I can only set my gyro gain to 45 on the gy401.

Any other ideas? I am (almost) loosing sleep over this!! Crying or Very sad
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Crashagain
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Joined: 17 Jan 2008
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PostPosted: Thu Jan 17, 2008 1:00 pm
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Do you have your tail rod as close as possible to the screw holding the control horn on?
If you are using an arm instead of the round wheel the linkage might be to far away and the servo can't move fast enough to compansate the distance. Ask me how I know... Confused
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maruey
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PostPosted: Fri Jan 18, 2008 12:27 am
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Crashagain wrote:
Do you have your tail rod as close as possible to the screw holding the control horn on?
If you are using an arm instead of the round wheel the linkage might be to far away and the servo can't move fast enough to compansate the distance. Ask me how I know... Confused


Yes I have it as close to the screw on the control horn. But still the tail wags. My gain is set at +35..

Maybe I'll go try the round wheel linkage. Would that work better you think?
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Crashagain
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PostPosted: Fri Jan 18, 2008 9:05 am
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I think that the round wheel gets the linkage a little closer to center.
That's why I chose it for mine.
I am running 65% gain on my gyro with no wag at all...




You know something I thought of....??


If you pop off the linkage from the tail and move that arm for the blades back and forth, is it smooth??
I had a problem with mine after changing the tailgear, I had a bind issue going on causing a wag.... Turned out that the 2 screws that held the plastic snap rings on were too tight.
Chekc that out too...
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maruey
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PostPosted: Sat Jan 19, 2008 5:06 pm
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Success!!!

Wow Crashagain thank you so much for your tip. You really saved my helicopter!! I did as you advised and wow!! The tail hold is so steady I couldn't believe it.

Got to tell you though that I couldn't the round wheel so I took the arm I was using and burnt a needle and created a new hole by my self. Of course, I aimed to get it as close as possible to the screw. It was slightly off center, but apparently it didn't matter!!

Before my gain was set at +35 but now I could push it all the way to +65. The hold was so steady I could literally take my hands of the controls for about 10 secs.

Thank you once again. You're the man CrashAgain!!! Mr. Green
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Crashagain
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PostPosted: Sun Jan 20, 2008 3:50 am
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Glad to hear you got it....
It's so nice when you can enjoy flying instead of wondering why it is not working right....

Glad to help..
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maruey
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PostPosted: Fri Feb 01, 2008 9:00 pm
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Hello all, just wanna post an update on the situation of my T-REX

So I drilled an extra hole in my servo horn and was able to get the gyro gain way up from before and my helicopter was flying steady. But not quite rock solid as I found out later that after about 10 seconds my helicopter's nose will want to drift right. At first I didn't know what to do but then I read an article here about the gyro stuff. So I found out that if the helicopter has a tendency to drift you have to twist the linkage which controls the tail rotor clockwise or counter clockwise depending on the symptom until the drifting stops. This is called "off setting" I think.

Anyways, so I tried that, at first I made my situation worse by turning the linkage the wrong way but after experimentation I found out that it did help!! And now I got my gyro gain to +70 and my T-REX is now even more solid than before Wink
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Crashagain
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PostPosted: Sat Feb 02, 2008 5:35 am
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I never heard of that..
Can you post the link for that article?
I'd love to read up on it.
I have a solid tail with the gain at 65% but I do that nose drift problem.
I just figured it was the nature of the beast...
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maruey
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PostPosted: Sun Feb 03, 2008 12:00 am
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Crashagain wrote:
I never heard of that..
Can you post the link for that article?
I'd love to read up on it.
I have a solid tail with the gain at 65% but I do that nose drift problem.
I just figured it was the nature of the beast...


Hi, yes of course, here's the article.

I think maybe you could try offsetting the linkage like I did, it might help. Cool
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Crashagain
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PostPosted: Sun Feb 03, 2008 2:14 am
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Thanks....
That's some interesting reading...
I'm going to give it a try and see what happens...
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Tirjfjjop
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Joined: 15 Aug 2015
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PostPosted: Sat Aug 15, 2015 9:40 pm
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It’s really great posts.
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